Every year, millions of dollars are spent repairing power line infrastructure and restoring power when adverse weather strikes. Power lines and utility poles can be broken due to high winds, ice buildup, or other severe weather conditions. There needs to be a way to protect the power lines and the utility poles from breaking under these conditions.

Background

Grid Defender (GD) is a utility pole support system invented and patented by Dennis Bell. This design allows the cross arms of utility poles that support power lines to be lowered to the ground if there is a excessive load on the poles or lines. When the cross arm is lowered, the flow of electricity is automatically cut within the sector. Once the storm or danger has passed, the utility company can send a team to raise the cross arms back into place with the use of a small motor. The intention of this design is to save infrastructure. By lowering the power lines, it is less likely that the poles will break and snap. This also introduces a new level of safety. The power will be cut to these lines, in the hopes that this device will reduce the number of electrocutions.

Deliverables

By the end of the Spring semester, we plan to build and test a full-scale single pole prototype on a shortened utility pole. This prototype will showcase the system dropping under a specific weight limit at the desired descent rate, as well as the method of resetting the system. The deliverables also include a small electrical system that will power a GPS device in order to send the location of the outage. The GPS will send a signal to a transceiver which will allow operators to pin point the location of the outage and send a crew to fix the problem. The intended communication system for multiple poles will be modeled by our computer science major as a tabletop display.

Specifications

The system is set to release once a 4000 pound threshold is reached, and descend at a rate under 8 ft/sec. Once the system starts dropping, a signal will be sent to the breakers on the ends of the GD sector to cut power in the lines. At the same time, a GPS node that is on each pole will send a signal to control indicating each dropped pole's location so a technician can easily locate and reset the downed poles.

Project Learning Overview

Mechanical Engineers:
Grid Defender's client, Dennis Bell, calls himself a "GearHead" and is familiar with the AutoCad software. To interface with him, the Senior Design team's mechanical engineers have explored how to utilize and understand AutoCad as well. These gentlemen then modeled the mechanical aspects of the Grid Defender system and researched winch systems and centrifugal breaking methods. They have learned how to analyze the additional loading created by adverse weather conditions and how to use that data to run stress analysis on individual parts in the system. A lot of valuable information has also been shared by the client and Dr. Perry, the team's lead instructor.

Electrical Engineers:
The electrical engineers on the team have explored different options for Grid Defender's breakers. In particular, 3 phase breakers and breaker standards for power poles. They have put a lot of time into research about which breakers will be best for this project based on safety and what will meet codes and standards, size, such that they are able to be mounted on distribution poles, and cost.
Additionally, lightning protection for the whole system was analyzed for this project.
The ability to independently power the system is the next phase on the electrical side that is being researched in order to find the most efficient way to power the communication system.

Computer Science:
The computer scientist on our team has focused on Grid Defender's communications. She spent the first semester in communication with engineers in industry, figuring out how best to obtain pole-to-pole communication. When the team decided that a multi-pole prototype was too ambitious, she shifted her focus from creating a full-sized communications system to making a tabletop demonstration piece. This interactive display will show how Grid Defender’s pole-to-pole communication system could track a sector’s status. To accomplish this, she has stepped beyond the realm of software and has been teaching herself about circuits, microcontrollers, and networking protocols.

Group Learning:
Collectively, the team has learned more about what it takes to work with a client to produce a quality product. They are now better at understanding a client's needs and deciding what can and cant be accomplished in a given amount of time. They have learned important lessons on the dangers of "scope creep" and to focus only on the project aspects that are relevant for this year. They also have a better understanding of each other's strengths and weaknesses and how to work cohesively and efficiently. They have gained experience in presenting their project in a professional manner through multiple snapshot days, client meetings, design reviews, and the recent pitch competition. They have practiced describing their project and design intent to people with varying degrees of previous knowledge of the power grid or engineering design in general.

Items Researched

Breaker

It was found that a breaker must be able to withstand a specific rated current when opening. Different breakers have different ratings that allow them to be used for both distribution lines and transmission lines. The opening of a circuit creates a large arc which is a safety concern. The best way to approach this problem was to use a breaker already utilized by the utility companies.

Lightning Arrestor

It was determined that the best way to approach lightning tolerance was to use lightning arrestors, a device already utilized by the power companies. This device acts as a lightning rod that will direct a lightening strike away from the apparatus being created.

Power Supply

Research to be performed is how to draw power from the lines in order to charge a battery. This battery will then be used to operate the GPS form of communication system that is currently being looked into.

Transceiver

Transceivers are used to transmit and receive data. There are various types of transceivers for different media. One option, pictured here, is the Schweitzer Engineering Laboratories' SEL-2814 for communication over fiber optic cable. This model does not perform encryption, but using a wired connection helps prevent eavesdropping and signal interference. Encryption is still encouraged for later versions of Grid Defender but may be performed separately.

GPS

The client for Grid Defender has included a GPS unit as part of his design patent. Initially, our intention was to have Grid Defender wait to power its GPS unit until its cross arm disengaged. However, this may cause an inaccurate reading. There are many factors that effect GPS output, so our computer science major recommends taking the average of several outputs instead. This would cause a delay, so she recommends calculating GPS information ahead of time and then caching it for later use.

Design Overview

Mechanical Engineers:
The role of the mechanical engineers is to design the physical components responsible for dropping and resetting the system. This includes everything from pole and cross arm size, to designing the winch assembly and cross arm docking means.

Electrical Engineers:
Breaker Selection: it was determined that the best option for the breaker was to utilize the breakers already on the system. These breakers meet the specifications necessary in order to open the lines safely and securely.

Computer Science:
A single-pole prototype was not sufficient to employ the pole-to-pole communications planned by their computer science major. Instead, she has reconfigured her design to work as an independent tabletop display.

Design Details

Physical System

The team has decided to go with a class 4, 35 foot pole, with the help of the inventor. The breaking system to control the rate of decent will utilize a centrifugal brake on a geared shaft. The gear ratio from the cable drum shaft to the brake shaft has been designed with a 3.5:1 ratio in order to activate the centrifugal brake at the correct RPM. All components for the system have been designed for longevity in the face of outdoor conditions. This means stainless steel and non-corrosive materials.

Winch Assembly

The release means to drop the system has been designed as a passive "break-away" device. It is located in the winch assembly rather than at the top of the pole, to make resetting the system easier since the winch assembly is at ground level. The size of the cable drum has been designed to only let the cable wrap around once, instead of wrapping multiple times over itself. This was decided so the moment arm on the shaft wont increase from the cable wrapping multiple times over itself.

GPS Circuit

The next phase in the design process is to create a small electrical circuit that will be used in order to power the communication system. This electrical circuit will need to pull power from the distribution lines that will charge a battery. The battery will then be used to power the communications when the system is in operation and the distribution line power is cut. The battery will need to be able to provide at least 4.2V in order to operate the GPS module.

Communications System

Most of Grid Defender's communications will take place locally through a dedicated cable. Each Grid Defender "sector" will comprise of standard units daisy chained together, with control units at each end. Each control units will monitor the status of the standard units in its sector(s). When a problem is reported, the control unit will send an alert to the nearest substation through a different, long-range communications medium. The exact nature of this long-range communications may vary, but example media include radio, microwave, and power line carrier signals.

Communications Display

Currently in development is an interactive tabletop display to demonstrate how Grid Defender's communications system will relay messages pole-to-pole.

Implementation & Testing

We plan to build and test a full scale prototype of a single apparatus, but on a shortened pole that we can work on in the shop. We will be testing the breakaway system to release at a desired threshold. We will also be testing to make sure the drop speed is within desired limits and the ease of resetting the system once it has correctly dropped.

Team Information

CodeSculptor

Develop and model Grid Defender's communications system and logic processing.

Organize/manage project documentation.

Help design Grid Defender to be robust, reliable, and secure.

Bio: CodeSculptor has a strong interest in data privacy. She takes care to protect her information whenever possible and is the sort of person who reads EULAs in full before agreeing to them.

Lexi Turkenburg

Engineering Major: Electrical Engineering (Power)
After graduating from the Coeur D Alene Charter Academy in 2013, Lexi started her college career at Montana Tech of the University of Montana. She then transferred to the University of Idaho where she is currently a senior in the Electrical Engineering department. Lexi will be graduating in May with her bachelors in Electrical Engineering with an emphasis in power.

Austin Amrein

Engineering Major: Electrical Engineering (Power)
After graduating from the Snohomish High School in 2013, Austin started college at The University of Idaho for Electrical Engineering. Austin will be graduating in May with his bachelors in Electrical Engineering with an emphasis in power. He has interned the past two summers at the Naval Reactors Facility (a facility that is part of the Idaho National Labratories working for the Navy and Department of Energy), in Scoville, Idaho and upon graduating from college he will be starting his career there in Power Engineering.

Shane Doll

Engineering Major: Mechanical Engineering
Born and raised in Post Falls Idaho. Mechanical Engineering major. Graduating in spring 2017 and wants to work in the field of engineering design with an emphasis in solid modeling. Likes sunsets and long walks on the beach.

Daniel Schlittler

Engineering Major: Mechanical Engineering
Daniel is a Mechanical Engineering major who loves Solid Modeling and Machining. He also loves Mechanics of Materials. Outside of school Daniel loves the outdoors. He loves to hunt and fish. Daniel will graduate in May with his Bachelors in Mechanical Engineering and hopes to work somewhere involving cars or atvs.

Justin Puryear

Engineering Major: Mechanical Engineering
Justin is a Senior Mechanical Engineer at the University of Idaho. He plans on graduating this May. His dream job is to start a Think Tank type of partnership with a few other engineers/business professionals and working on brainstorming and innovating products that could be implemented throughout society.